1. Technical Field
The present invention relates to a technique for reducing display unevenness in the case of controlling luminance by performing pulse width modulation (PWM) of a light source.
2. Related Art
The luminance of a light source, such as a laser diode (LD) or a light-emitting diode (LED), can be easily adjusted by performing PWM control. This is because PWM is excellent in terms of being established using a digital circuit and ensuring the stability of the light intensity and the circuit. Under such circumstances, a technique in which such a light source is applied to, for example, a projector, has been suggested, for example, in JP-A-2004-354717. In this technique, color changes are reduced, and a display dynamic range is apparently increased.
However, there has been a problem in that PWM control of a light source causes a phenomenon (scroll noise) where band-shaped bright and dark portions extending in a horizontal direction move slowly upward or downward on the screen and that the quality of display is thus severely degraded.